Quinoline derivatives and organic electroluminescent devices

ABSTRACT

Quinoline derivatives represented by formula (1) wherein two or more of substituents R 1  to R 7  are each a group of formula (2). In general formula (2), Q is a carbo- or hetero-aryl group; and the number (n) of double bonds is preferably 1 to 3. Use of such derivatives in an organic EL device provided with a layer of an organic compound and two electrodes sandwiching the layer as the organic compound gives devices emitting yellow to red light with high brightness and high efficiency. Further, doping a hole transport layer with such derivatives realizes organic EL devices capable of emitting lights of resultant colors (e.g., white) composed of lights from light-emitting and hole transport layers.

TECHNICAL FIELD

The present invention relates to an organic compound useful as a lightemitting material for an organic electroluminescence element(hereinafter referred to as an “organic EL element”) and a lightemitting material for other electronic device materials or the like, andto an element employing such organic compound.

BACKGROUND ART

Organic EL elements are constructed by layering, on a transparent glasssubstrate, a transparent first electrode (for example, ITO), an organiccompound layer which includes an organic compound having strongfluorescence, and a metal (for example, Mg) second electrode in thatorder.

The organic layer has, for example, a three-layer structure in which alayer of molecules having a hole transport function, a layer ofmolecules having an emissive function, and a layer of molecules havingan electron transport function are layered in that order, and emitslight when an electric field is applied to the pair of electrodes. Inother words, when holes are injected from the first electrode andelectrons are injected from the second electrode, the injected holes andelectrons move through the hole transport functional molecule layer, theemissive functional molecule layer, and the electron transportfunctional molecule layer of the organic layer, such that the holes andelectrons collide, recombine, and disappear. The energy generated bythere combination is used for producing exited states of the emissivemolecules and fluorescence is emitted from the organic EL element.

In such an organic EL element, an aluminum quinolinol complex (Alq₃)represented by a chemical formula (3),

is well known as a light emitting material having a quinoline ring. Thiscompound is obtained by substituting a hydroxy group into the quinolinering to form a complex with aluminum and emits a green light.

As a red light emitting material for an organic EL element, aphthalocyanine derivative as disclosed in Japanese Patent Laid-OpenPublication No. Hei 7-288184 and a porphyrin derivative as disclosed inJapanese Patent Laid-Open Publication No. Hei 9-296166 are known.

Because all of the known light emitting materials having the quinolinering such as Alq₃ have a short conjugate system, light emitting functionhas so far been obtained only in the blue˜green range. To realize acolor organic EL element, it is necessary to obtain a compound whichemits light with sufficient characteristics for other colors,specifically those in the yellow˜red range.

On the other hand, although the phthalocyanine derivative and porphyrinderivative as described above have a red light emitting function, theydo not have sufficient luminance nor sufficient endurance, and, thus, donot satisfy all the requirements desired for applications such as in anorganic EL element.

The present invention was conceived to solve the problem describedabove, and one object of the present invention is to provide a novelorganic compound having superior stability and light emitting luminancecharacteristic and having light emitting function in yellow˜red range,and an organic EL element which employs such organic compound.

DISCLOSURE OF INVENTION

In order to achieve at least the object described above, according tothe present invention, there is provided a quinoline derivative compoundrepresented by a chemical formula (1),

wherein at least two of the substituents R₁˜R₇ in the chemical formula(1) have a structure represented by a chemical formula (2),

where Q in the chemical formula (2) is an arbitrary functional group.

In the novel organic compound, at least two substituents having a doublebond in the structural formula (chemical formula (2)) are introduced assubstituents for the quinoline ring (chemical formula (1)). Because ofthis, the compound has a structure in which the conjugate system is longand the energy difference between the excited state and the ground stateof the compound is small and, thus, light emission function in theyellow˜red range can be obtained.

According to another aspect of the present invention, it is preferablethat, in the organic compound represented by the chemical formula (1),at least one of the substituents R₁˜R₇ other than the substituentshaving a structure represented by the chemical formula (2) is anelectron attracting substituent.

By introducing an electron attracting substituent as a substituent inthe quinoline ring, the fluorescence quantum yield of the compound canbe improved and, as a result, a light emitting material which can emitlight at higher luminance and higher efficiency can be obtained.

According to another aspect of the present invention, it is preferablethat, in the organic compound, Q in chemical formula (2) is an aromaticgroup having carbon or aheteroatomin the skeleton of the ring and atleast one of the substituents R_(Q) of the aromatic group Q is anelectron donating substituent.

By using a stable aromatic group as Q, it is possible to preventreactions of the double bonds in the chemical formula (2) and therebyimprove the stability as a compound. Furthermore, by using at least oneelectron donating substituent for the substituents R_(Q), thefluorescence quantum yield of the overall compound represented by thechemical formula (1) can be improved. In particular, it is preferablethat an electron attracting group is introduced to at least one of thesubstituents R₁˜R₇ of the quinoline ring and an electron donating groupis introduced as the substituent R_(Q) of Q. More preferably, a cyanogroup is used for the subsituent R₃ and a p-aminophenyl group is usedfor the substituent Q. With such a structure, the fluorescence quantumyield of the compound is further improved, and a light emitting materialhaving even higher luminance and higher efficiency can be obtained.

According to another aspect of the present invention, it is preferablethat, in the organic compound, the number n of the double bonds in thechemical formula (2) be, for example, at least 2 or no more than 5, orit is also preferable that the number n of the double bonds in thechemical formula (2) be in the range of 1˜3.

When the value of n is in the range of 1˜3 or 2 or greater, a highlystable compound can be obtained which allows for improvements in theendurance of an element when the compound is used, for example, in anorganic compound layer of an organic EL element, as will be describedbelow.

According to another aspect of the present invention, it is preferablethat the substituents R_(n) and R′_(n) in the chemical formula (2) arecyclized. Through the cyclization, free rotation which is normallygenerated in a vinyl group represented by the chemical formula (2) canbe blocked, and the link in the conjugated system can be maintained.Moreover, separation of the n-bonds within the molecule and alterationof the molecular shape can also be prevented, allowing for improvementin the endurance or the like of the molecule.

According to another aspect of the present invention, there is providedan organic electroluminescence element wherein an organic compound layerwhich includes an emissive layer is formed between two electrodes, andthe organic compound described above, that is, an organic compoundrepresented by the chemical formula (1) and having at least two of thesubstituents R₁˜R₇ substituted by a substituent represented by thechemical formula (2), is used for the organic compound layer.

As described above, because the organic compound according to thepresent invention has a light emitting characteristic in the yellow˜redrange, by using the organic compound as the material for the organiccompound layer, in particular, for the emissive layer, of the organic ELelement, an organic EL element having high luminance, high efficiency,and high stability can be obtained.

According to another aspect of the present invention, it is preferablethat, in the organic electroluminescence element, the organic compoundlayer comprises a hole transport layer and an emissive layer, and anyone of the quinoline derivative compounds described above is doped intothe hole transport layer.

According to another aspect of the present invention, there is providedan organic electroluminescence element wherein an organic compound layerwhich includes an emissive layer is formed between two electrodes, theorganic compound layer comprises a blue emissive layer and a holetransport layer doped with any one of the quinoline derivative compoundsas described above, and the organic electroluminescence element emitswhite light.

As described above, the quinoline derivative compound of the presentinvention not only demonstrates light emission characteristic ofyellow˜red range when used alone, but also produces a light in a similarwavelength range in a hole transport layer when the quinoline derivativecompound is doped to the hole transport layer. Therefore, in an organicEL element, light can be emitted having a color determined by thesynthesis of the light from the emissive layer and the light from thehole transport layer. For example, by using a blue light emittingmaterial for the emissive layer and the quinoline derivative compoundaccording to the present invention as the doping material of the holetransport layer, it is possible to obtain a white light emitting organicEL element through the synthesis of the blue light from the blueemissive layer and the light in the orange˜red range from the holetransport layer. In such a case, because the synthesized color can beobtained merely by doping the hole transport layer, there is no need toincrease the number of emissive layers.

By using, for the organic compound layer of the element as describedabove, an organic compound in which an electron attracting substituentis introduced to at least one of the substituents R₁˜R₇ other than thesubstituents substituted by the substituent represented by the chemicalformula (2), an organic EL element can be obtained which has even higherlight emitting efficiency or which is capable of being driven at a lowvoltage. In addition, by introducing an electron donating substituent asa substituent R_(Q) of Q (aromatic group) in the chemical formula (2),further improvements in the light emitting efficiency can be realized.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a structure of an organic EL elementaccording to a first embodiment of the present invention.

FIG. 2 is a diagram showing a structure of an organic EL elementaccording to a second embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

10 SUBSTRATE (TRANSPARENT SUBSTRATE, GLASS SUBSTRATE), 12 FIRSTELECTRODE (ANODE), 14 ORGANIC COMPOUND LAYER, 16 SECOND ELECTRODE(CATHODE), 22 HOLE TRANSPORT LAYER, 24 EMISSIVE LAYER, 26 ELECTRONTRANSPORT LAYER.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the invention (hereinafter referred to as“the embodiments”) will now be described with reference to the drawings.

FIG. 1 schematically shows a structure of an organic EL elementaccording to a first embodiment of the present invention.

The element is constructed by layering a first electrode 12, an organiccompound layer 14 which emits light through application of an electricfield, and a second electrode 16, in that order, on a transparentsubstrate 10.

As the transparent substrate 10, a glass substrate, a transparentceramic substrate, a diamond substrate, or the like can be used. As thefirst electrode 12, a transparent electrode having a high lighttransmittance and electrical conductivity is used. For example, a thinfilm material such as ITO (Indium Tin Oxide), SnO₂, In₂O₃, orpolyaniline can be used.

The organic compound layer 14 is a section which emits light throughapplication of an electric field, and has a structure such as, forexample, a single layer structure of an emissive layer, a two-layerstructure of a hole transport layer and an emissive layer, or athree-layer structure of a hole transport layer, an emissive layer, andan electron transport layer. The organic compound layer 14 may be formedas a single layer or a multi-layer structure. The thickness of theorganic compound layer 14 is in the range of several tens of nanometersto several hundreds of nanometers.

In the first embodiment, a quinoline derivative compound according tothe present invention and having a structure which will be describedbelow is used as the material having light emitting function in theorganic compound layer 14. The quinoline derivative is capable offorming an emissive layer of the organic EL element as a single entity.It is also possible to form the emissive layer using a known lightemitting compound as a host material such as, for example,distyrylarylene derivative (DPVBi) represented by the following chemicalformula (4), Alq₃, and a derivative of Alq₃, and doping, into the hostmaterial, for example, on the order of a few percent of a quinolinederivative compound according to the present invention and which will bedescribed below.

As the hole transport layer and the electron transport layer etc., anyknown molecules having hole transport functionality and any knownmolecules having electron transport functionality can be used. Moleculeshaving hole transport functionality include, for example,copper-phthalocyanine and tetramer of triphenylamine (TPTE). Moleculeshaving electron transport functionality include, for example, Alq3 orthe like which also has a light emitting function as described above.

As the second electrode 16 to be formed over the organic compound layer14, a metal electrode such as, for example, Mg, Ag, a Mg—Ag alloy, anAl—Li alloy, and LiF/Al can be used.

In an organic EL element having such a structure, the first electrode 12is used as an anode and the second electrode 16 is used as a cathode.Holes and electrons are injected from these electrodes into the organiccompound layer 14. In the organic compound layer 14, the injected holesand electrons recombine, the light emitting material is excited, andfluorescence of the quinoline derivative according to the presentinvention in the yellow˜red range can be obtained.

An organic EL element according to a second embodiment of the presentinvention will now be described with reference to FIG. 2. An organiccompound layer 14 has a structure wherein at least a hole transportlayer 22 and an emissive layer 24 are layered on a first electrode 12 inthat order. In addition, in the example shown in FIG. 2, an electrontransport layer 26 is formed between the emissive layer 24 and a secondelectrode 16.

In the second embodiment, the emissive quinoline derivative compoundaccording to the present invention as will be described below isincluded in the hole transport layer 22, and light emission of asynthesized color can be realized through combination of the holetransport layer 22 and the emissive layer 24 (or alternatively, anemissive layer which also has the electron transport functionality) inwhich a light emitting material of a desired color is used. In otherwords, not only can the quinoline derivative compound according to thepresent invention produce a fluorescence of yellow˜red range when usedalone, but can also realize a fluorescence of similar wavelength range(orange˜red range) when the quinoline derivative compound is doped tothe hole transport layer. Therefore, by using a blue emissive materialfor the emissive layer and the quinoline derivative compound of thepresent invention as the doping material of the hole transport layer, itis possible to obtain an organic EL element having white light emittingcharacteristic through synthesis of the blue light from the blueemissive layer and the orange red light from the hole transport layer.The other structures are identical to those in the first embodiment.

As described above for the first embodiment, the quinoline derivativecompound according to the present invention which will be describedbelow can emit light when doped to the emissive layer. In addition, asdescribed above, the quinoline derivative compound can also emit lightby being doped into the hole transport layer. Therefore, when, forexample, a white light emitting organic EL element is created bycombining this compound with another light emitting material, there isno need to provide two emissive layers, that is, it is not necessary toprovide an emissive layer for each of materials emitting differentcolor. Because of this, it is possible to realize a white light emittingelement using the layered structure as shown in FIG. 2 (hole transportlayer/emissive layer/electron transport layer) which is already beingproposed and doping the organic compound according to the presentinvention to the hole transport layer.

Because the quinoline derivative compound according to the presentinvention as described below can emit light when doped, the amount ofmaterial required can be reduced compared to the case where the materialis used as the principle constituent of the emissive layer, allowing forminimization of cost of the material for manufacture when a white lightemitting element is realized using two light emitting materials.

Furthermore, because it is possible to adjust the color of the emittedlight by adjusting the amount of doping to the hole transport layer, thethickness of the hole transport layer, the thickness of the emissivelayer, etc., adjustment for obtaining a desired white color light isfacilitated.

DESCRIPTION OF THE ORGANIC COMPOUND OF THE INVENTION

An organic compound according to the present invention will now bedescribed. The compound has a structure in which at least two of thesubstituents R₁˜R₇ in a quinoline ring represented by the followinggeneral chemical formula (1) are substituted by a substituentrepresented by the following chemical formula (2) and having n doublebonds (where n is an integer greater than or equal to 1).

Because two or more substituent shaving a structure represented by thechemical formula (2) are introduced as the substituents for thequinoline ring represented by the chemical formula (1), the conjugatedsystem of the over all molecule is elongated and the energy differencesbetween the ground state and an excited state are reduced. Thus, forexample, by using the compound as a single entity in an emissive layerof an organic EL element or by mixing the compound with another lightemitting material (for example, as a doping material to a hostmaterial), a light emitting functionality in the range of wavelengths inyellow˜red can be obtained which emits light of a wavelength longer thanthat emitted when known Alq₃ (which emits green light) having aquinoline ring is employed.

It is particularly preferable that the terminal group Q in the chemicalformula (2) be an aromatic group (aromatic hydrocarbon group or aromaticheterocyclic group). One example of a suitable terminal group Q is aphenyl group represented by the following chemical formula (Q).

The substituents R₁˜R₇ that are not substituted by a substituentrepresented by the chemical formula (2) are independent from each other,and hydrogen atom or any arbitrary substituent other than the hydrogenatom can be employed. For example, any of a hydrogen atom, a hydroxygroup, a halogen atom, an alkyl group, an alkyl thio group, an arylgroup, an aryl thio group, an aryl oxy group, an alkoxy group, an aminogroup, a cyano group, a nitro group, an ester group, a carboxyl group, aheterocyclic group, and derivatives of these groups can be employed.Each of the substituents can be further substituted by anothersubstituent. Moreover, among the groups other than the substituentssubstituted by the substituent represented by the chemical formula (2),any one of pairs R₁ and R₂, R₂ and R₃, R₃ and R₄, R₄ and R₅, R₅ and R₆,and R₆ and R₇ may be bonded to form an aromatic ring or an aliphaticring, and the aromatic ring or the aliphatic ring may be substituted byother substituents. Substituents that can be employed as thesubstituents of the aromatic ring or the aliphatic ring are similar tothe functional groups listed above. Furthermore, in addition to thefunctional groups formed of carbon and hydrogen such as a benzene ringand naphthalene ring, the bonded aromatic ring or aliphatic ring mayalso be a ring including a heteroatom. Examples of a heteroatom includenitrogen, oxygen, sulfur, and silicon.

For the substituents R_(n), and R′_(n), in the chemical formula (2), anyarbitrary functional group may be employed. These substituents R_(n) andR′_(n) are independent from each other, and the examples include ahydrogen atom, a hydroxy group, a halogen atom, an alkyl group, an alkylthio group, an aryl group, an aryl thio group, an aryl oxy group, analkoxy group, an amino group, a cyano group, a nitro group, an estergroup, a carboxyl group, a heterocyclic group, and derivative groups ofthese groups, for example, a substituent in which a portion of thesubstituent is substituted by any of the listed substituents. When thenumber n in the chemical formula (2) is 2 or greater, the substituentsR_(n) and R′_(n) of the double bond may all be the same, all bedifferent, or some may be the same. As will be exemplified later, byusing a structure in which the R_(n) and R′_(n) are cyclized, it ispossible to block free rotation of the carbon atoms that are doublybonded in the chemical formula (2). Because of this, it is possible toprevent alteration of the torsional structure of the molecule of thequinoline derivative compound of the present invention, to reducecutting of the n bond within the molecule, and to facilitate retentionof the molecular shape, resulting in the possibility of significantimprovements in the thermal durability and stability of light emissionin a thin film for which the material is used.

Example compounds having the characteristics described above include thefollowing compounds represented by the chemical formulae (5)˜(13) and(14)˜(16).

In the compounds represented by the chemical formulae (5)˜(13),substituents represented by the chemical formula (2) are introduced atthe R₁ and R₃ positions in the quinoline ring represented by thechemical formula (1). In the compounds represented by the chemicalformulae (14)˜(16), substituents represented by the chemical formula (2)are introduced at the R₁ and R₅ positions in the quinoline ringrepresented by the chemical formula (1).

(i) Terminal Q in the Chemical Formula (2)

An aromatic group (aromatic hydrocarbon group or aromatic heterocyclicgroup), such as the phenyl group described above, may be preferablyemployed as the terminal Q because when an aromatic group is present asthe terminal, the reactivity of n double bonds in the chemical formula(2) can be reduced and the stability of the compound can be improved.The substituents R_(Q) of the terminal Q (substituents R₈˜R₁₂ in theabove described phenyl group) are not limited and are independent fromeach other. For example, a hydrogen atom, a hydroxy group, a halogenatom, an alkyl group, an alkyl thio group, an aryl group, an aryl thiogroup, an aryl oxy group, an alkoxy group, an amino group, a cyanogroup, a nitro group, an ester group, a carboxyl group, a heterocyclicgroup, derivatives of these functional groups (for example, asubstitution product in which a portion is substituted by any of thelisted functional groups), or the like can be employed. It is alsopossible for the substituents R_(Q) to have a structure such that theadjacent substituents R_(Q) (for example, R₈ and R₉, R₉ and R₁₀, R₁₀ andR₁₁, and R₁₁ and R₁₂) are bonded to each other to form an aromatic ringor an aliphatic ring. Moreover, the structure may also be such that thearomatic ring or the aliphatic ring is substituted by any of the listedfunctional groups. Furthermore, these aromatic group and aliphatic groupmay include a heteroatom within the ring. Example of the heteroatominclude, for example, nitrogen, oxygen, sulfur, and silicon.

As the terminal Q, the structures similar to the compounds representedby the following chemical formulae (17)˜(24) can be employed.

In the above compounds, as the terminal Q in the chemical formula (2), aphenyl group (for example, chemical formula (17)), a pyrenyl group (forexample, chemical formula (18)), an anthryl group (for example, chemicalformula (19)) or the like is employed. In these examples, as thesubstituents R_(Q) of the terminal Q, an amino group (for example,chemical formulae (17) and (20)), an isopropyl group or a t-butyl group(for example, chemical formula (22)), a structure in which adjacentgroups are bonded to each other to form an aliphatic ring (for example,a julolidyl group in the chemical formula (24)), or the like isemployed.

(ii) Substituents Among the Substituents R₁˜R₇ in the Chemical Formula(1) Other than the Substituents Substituted by a Functional GroupRepresented by the Chemical Formula (2)

As described, at least two of the substituents in the quinoline ring aresubstituents represented by the chemical formula (2), and the remainingsubstituents are not limited. However, it is preferable that an electronattracting substituent is introduced to at least one of the remainingsubstituents among the substituents R₁˜R₇. When an electron attractingsubstituent is introduced in this manner, the fluorescence quantum yieldof the compound is improved, and, when the compound is used as thematerial for the emissive layer, for example, to form an organic ELelement, it is possible to obtain an element having a high emissionluminance. Examples of electron attracting substituents include ahalogen atom, a cyano group, an ester group, a nitro group, a carbonylgroup, and an alkyl group and an aryl group substituted by these listedfunctional groups.

For example, it is possible to employ functional groups represented bythe following chemical formulae (25)˜(27) and (28˜(30) as an electronattracting substituent for introduction to the quinoline derivativecompound according to the present invention.

In the above compounds, for example, in the chemical formulae (25) and(28), cyano groups are employed, in the chemical formula (26), achlorine atom is employed, and in the chemical formulae (27), (29), and(30), phenyl groups which includes an electron attracting functionalgroup (an alkyl group to which a cyano group, a halogen atom, or thelike is introduced) are employed.

(iii) Substituents R_(Q) of the Terminal Group Q of Chemical Formula (2)

In the present invention, the substituents R_(Q) are not limited to anyparticular subsituent. However, by employing an electron donatingsubstituent, it is possible to improve the fluorescence quantum yield ofthe organic compound and to obtain an organic EL element having a highemission luminance by using such a compound as the light emittingmaterial. Examples of electron donating substituents include an aminogroup, an alkoxy group, an alkyl thio group, an alkyl group, and anamino group substituted by an alkyl group. Also, by employing astructure in which any of the listed electron donating substituents isintroduced to an aromatic ring or an aliphatic ring in cases whereadjacent substituents R_(Q) (for example, in the above chemical formula(Q), R₈ and R₉, R₉ and R₁₀, R₁₀ and R₁₁, and R₁₁ and R₁₂) are bonded toeach other to form an aromatic ring or an aliphatic ring, it is possibleto improve the fluorescence quantum yield, similar to the above.

(iv) Interaction Between the Substituents R₁˜R₇ and the SubstituentsR_(Q) of the Terminal Group Q of Chemical Formula (2)

By both introducing an electron attracting functional group to at leastone of the substituents R₁˜R₇ of the quinoline ring which are notsubstituted by the functional group represented by the chemical formula(2) as described above in (ii) and introducing an electron donatingfunctional group into at least one of the subsitutents R_(Q) of theterminal group Q of the chemical formula (2) as described above in(iii), it is possible to further improve the fluorescence quantum yieldin comparison to a compound that satisfies only one of the conditions(ii) and (iii). Therefore, by using a compound which satisfies thiscondition (iv), it is possible to obtain a brighter organic EL element.

Example compounds satisfying the above conditions include the compoundsrepresented by the following chemical formulae (31)˜(34) and (35)˜(39).

Moreover, it is possible to obtain a red-based light emitting materialhaving a superior stability and thermal endurance by employing a CNgroup having a superior electron attracting capability in thesubstituent R₃ of the quinoline ring represented by the chemical formula(1) and a p-aminophenyl group having a superior electron donatingcapability as the terminal group Q of the chemical formula (2), as shownin the above chemical formula (36).

(v) Number n of the Vinyl Group in the Chemical Formula (2)

As stated above, the number n (a number greater than or equal to 1) inthe chemical formula (2) is not limited. However, it is preferable thatn be 5 or less. If the number n becomes equal to or greater than 6, thestability of the compound is degraded and a highly durable elementcannot be obtained when the compound is used for an organic EL element.It is still more preferable that the number n be an integer in the rangeof 1˜3. When the number n is within the range of 1˜3, the compound ishighly stable, and the endurance of the organic EL element can beimproved when the compound is used for the organic EL element.

Also, when the number n is within the range of 1˜3, the light emittingefficiency is improved, and, thus, a compound which is superior as amaterial having a light emitting functionality can be obtained. Inparticular, when the number n equals 2, the light emitting efficiency ofthe compound is further improved. For example, when an emissive layer ofan organic EL element is formed by doping a compound in which the numbern is within the range of 1˜3, and, in an optimal case, equals 2, to ahost material, the compound not only is highly stable, but also canefficiently receive energy from the host material and emit light,thereby allowing for a highly efficient light emission.

(vi) Endurance

As described above in (v), in a compound in which the n is 5 or less, inparticular, in a range of 1˜3, because of reasons such as an increase inthe molecular weight, molecules of such a compound are relativelyimmovable in a film when a thin film is made from the compound, andthus, the stability of the film, that is, the endurance of the film, canbe improved.

Moreover, when a bulky functional group is employed as the terminalgroup Q in the chemical formula (2) to be introduced to the quinolinering and as the functional group (for example, an electron attractinggroup) to be introduced to the remaining substituents of the quinolinering, the crystallinity of the molecule is reduced because of sterichindrance or the like. By forming a film using such a compound includinga bulky functional group, the cohesion of the compound within the filmoccurs less frequently, resulting in improvements in the thermaldurability (endurance) of the film.

Furthermore, superior characteristics can be obtained in quinolinederivative compounds having structures represented by the followingchemical formulae (40)˜(45).

In these compounds, the number n in the chemical formula (2) is set at2, a substituent having a superior electron attracting capability suchas, for example, a cyano group, a p-cyano phenyl group, and3,5-bis(trifluoromethyl)phenyl group is introduced to the substituentR₃, substituents having a superior electron donating capability such as,for example, ap-aminophenyl group and a julolidyl group is introduced asthe substituent Q to the substituents R₁ and R₅, and R_(n) and R′_(n) inthe chemical formula (2) are cyclized. In such a structure, themolecular structure is stable, and, when a thin film is made, the filmhas a superior endurance. Moreover, a longer chain of n bonds is presentwithin the molecule and superior light emitting characteristic can berealized. Furthermore, these molecules demonstrate a light emittingcharacteristic even when doped to the hole transport layer, and it istherefore possible to easily obtain a color synthesized with the lightfrom the emissive layer. In particular, by combining a blue emissivelayer and a hole transport layer which is doped by these quinolinederivative compounds, it is possible to easily realize a superior whitelight emitting organic EL element.

EXAMPLES

Specific examples of the realization of the present invention andcomparative examples will now be described.

Example 1-1

Synthesis of a Compound Represented by the Chemical Formula (20)

In example 1-1, a compound represented by the above chemical formula(20) was synthesized as an example quinoline derivative compound throughthe following processes.

2,4-dimethylquinoline (2.0 g), N-bromosuccinimide (4.5 g), benzoylperoxide (500 mg), and CCl₄ (50 ml) were mixed and heated and refluxedfor 2 hours in a nitrogen atmosphere. The reaction solution was cooledto room temperature and succinimide produced through the reaction wasremoved by filtering. The solvent was removed under reduced pressure andthe residue was purified through column chromatography (silica gel,hexane/ethyl acetate=4/1) to obtain 2,4-bis(bromomethyl)quinoline (0.93g).

A toluene solution (5 ml) of the 2,4-bis(bromomethyl)quinoline thusobtained (0.93 g) and triethyl phosphite (3.3 ml) were heated in anitrogen atmosphere for 3 hours at a temperature of 140° C. The reactionsolution was cooled to room temperature and excessive triethyl phosphiteand toluene were removed, to obtain coarse refinement of Wittig reagentof 2,4-bis(bromomethyl)quinoline.

A DMF (N,N-dimethylformamide) (2 ml) solution of the coarse refinementof Wittig reagent of 2,4-bis(bromomethyl)quinoline obtained as above andN,N-dimethylaminocinnamaldehyde) (0.35 g) were dropped to a mixture ofsodium t-butoxide (0.38 g) and DMF (2 ml) in a nitrogen atmosphere andat room temperature, and the reaction solution was stirred for 2 hoursat room temperature. Water was added to the reaction solution andorganic layer was extracted using ethyl acetate. The organic layer wasdried by Na₂SO₄ and the Na₂SO₄ was then removed by filtering. Thesolvent was removed under reduced pressure and the residue was purifiedthrough column chromatography (silica gel, hexane/ethyl acetate=3/2) toobtain a compound represented by the chemical formula (20) (0.3 g).

Example 1-2

Synthesis of a Compound Represented by the Chemical Formula (34)

In this example 1-2, a compound represented by the above chemicalformula (34) was synthesized as an example quinoline derivative. Thecompound represented by the chemical formula (34) was obtained through amethod similar to the example 1-1 for synthesis of the compoundrepresented by the chemical formula (20) except that2,4-dimethyl-3-[3,5-bis(trifluoromethyl)phenyl]quinoline was used inplace of 2,4-dimethylquinoline.

2,4-dimethyl-3-[3,5-bis(trifluoromethyl)phenyl]quinoline was synthesizedthrough the following processes. First, 2,3-dimethylindole (1.0 g),triethylbenzylammonium chloride (0.17 g), CHCl₃ (10 ml), and an aqueoussolution of NaOH (33%, 5 ml) were mixed at a temperature of 0° C. andwere stirred for 6 hours at 0° C. and then for 24 hours at roomtemperature. The organic layer was extracted using CHCl₃ and the solventwas removed under reduced pressure. The residue was purified throughcolumn chromatography (silica gel, hexane/ethyl acetate=3/1) to obtain2,4-dimethyl-3-chloroquinoline (0.65 g).

To a THF solution of the obtained 2,4-dimethyl-3-chloroquinoline (0.65g) and Ni(dpp)Cl₂ (dpp: 1,3-bis(diphenylphosphino)propane) (0.1 g),3,5-bis (trifluoromethyl)phenylmagnesium bromide prepared from Mg and3,5-bis(trifluoromethyl)bromobenzene was dropped and the reactionsolution was allowed to react for 24 hours at room temperature. Waterwas added to the reaction solution and the organic layer was extractedusing CHCl₃. The solvent was removed under reduced pressure and theresidue was purified through column chromatography to obtain2,4-dimethyl-3-[3,5-bis(trifluoromethyl)phenyl]quinoline.

Example 1-3

Synthesis of a Compound Represented by the Chemical Formula (35)

In the example 1-3, a compound represented by the chemical formula (35)was synthesized. The compound represented by the chemical formula (35)was obtained through a synthesis similar to example 1-1 for synthesizingthe compound represented by the chemical formula (20), except that2,6-dimethyl-4-[3,5-bis(trifluoromethyl)phenyl]quinoilne was used inplace of 2,4-dimethylquinoline and a compound represented by thefollowing chemical formula (46) was used in place of theN,N-dimethylaminocinnamaldehyde.

2,6-dimethyl-4-[3,5-bis(trifluoromethyl)phenyl]quinoline was synthesizedthrough the following processes.

First, 3,5-bis(trifluoromethyl)phenylmagnesium bromide prepared from Mgand 3,5-bis(trifluoromethyl)bromobenzene was dropped into a THF solutionof 4-chloro-2,6-dimethylquinoline (1 g) andNi(dpp)Cl₂ (dpp:1,3-bis(diphenylphosphino)propane) (0.1 g). Reactions were allowed totake place for 24 hours at room temperature. Water was added to thereaction solution and the organic layer was extracted using CHCl₃. Thesolvent was removed under reduced pressure and the residue was purifiedthrough column chromatography to obtain2,6-dimethyl-4-[3,5-bis(trifluoromethyl)phenyl]quinoline (0.5 g).

Example 1-4

Synthesis of a Compound Represented by the Chemical Formula (36)

In example 1-4, a compound represented by the chemical formula (36) wassynthesized through the following processes as an example quinolinederivative.

First, 4-bromo-2,6-dimethylquinoline (5.0 g) and CuCN (4.82 g) wereadded to DMF (70 ml) and were allowed to react for 6 hours at atemperature of 140° C. Ice was poured to the reaction solution and theproduced precipitate was removed through filtering. The filtrate wasextracted using ethyl acetate, the solvent was removed under reducedpressure, and the residue was purified through column chromatography(silica gel, hexane/ethyl acetate=4/1) to obtain4-cyano-2,6-dimethylquinoline (2.14 g) represented by the followingchemical formula (47).

The 4-cyano-2,6-dimethylquinoline (2.0 g), n-bromosuccinimide (3.91 g),benzoyl peroxide (0.430 g), and CCl₄ (50 ml) were mixed and heated andrefluxed for 1.5 hours in a nitrogen atmosphere. The reaction solutionwas cooled to room temperature and succinimide produced through thereaction process was removed by filtering. The solvent was removed underreduced pressure and the residue was purified through columnchromatography (silica gel, hexane/ethyl acetate=4/1) to obtain4-cyano-2,6-bis(bromomethyl) quinoline (0.18 g).

A toluene (1 ml) solution of the 4-cyano-2,6-bis (bromomethyl) quinoline(0.80 g) and triethyl phosphite (1 ml) was heated for 2.5 hours in anitrogen atmosphere at a temperature of 140° C. The reaction solutionwas cooled to room temperature and excessive triethyl phosphite andtoluene were removed to obtain a coarse product of Wittig reagent of4-cyano-2,6-bis(bromomethyl)quinoline.

A DMF (N,N-dimethylformamide) (2 ml) solution of the coarse product ofthe Wittig reagent of 4-cyano-2,6-bis(bromomethyl)quinoline andN,N-dimethylaminocinnamaldehyde (0.124 g) was dropped into a mixture ofsodium t-butoxide (0.091 g) and DMF (2 ml) in a nitrogen atmosphere atroom temperature and stirring was performed for 3 days at roomtemperature. Water was added to the reaction solution and the producedprecipitate was filtered. The precipitate was washed by a CCl₄ water andvacuum dried to obtain a compound represented by the chemical formula(36) (0.10 g).

Example 1-5

Synthesis of a Compound Represented by the Chemical Formula (37)

In example 1-5, a compound represented by the chemical formula (37) wassynthesized through the following processes as an example quinolinederivative. A DMF (2 ml) solution of the coarse product of Wittigreagent of 4-cyano-2,6-bis(bromomethyl)quinoline which was synthesizedthrough a process similar to the process for the above compoundrepresented by the chemical formula (36) and aldehyde (0.160 g)represented by the chemical formula (47) was dropped to a mixture ofsodium t-butoxide (0.091 g) and DMF (2 ml) in a nitrogen atmosphere andat room temperature, and stirring was performed for 5 days at roomtemperature. Water was added to the reaction solution and the producedprecipitate was filtered. The precipitate was washed by CCl₄ water andvacuum dried to obtain a compound represented by the chemical formula(37) (0.108 g).

Example 1-6

Synthesis of a Compound Represented by the Chemical Formula (38)

In example 1-6, a compound represented by the chemical formula (38) wassynthesized through the following processes as an example quinolinederivative. First, a solution in which 4-bromo-2,6-dimethylquinoline(1.05 g) identical to that in the example 1-4 and Pd(Ph₃P)₄ (0.31 g)were added to toluene (8.5 ml), a solution in which Na₂CO₃ (1.81 g) wasadded to water (8.5 ml), and a solution in which 4-cyanophenylboric acid(0.726 g) was added to methanol (2.8 ml) were mixed and allowed to reactfor 22 hours in a nitrogen atmosphere at a temperature of 80° C. Thereaction solution was poured into water and extracted using chloroform.The chloroform layer was dried using Na₂SO₄ and the Na₂SO₄ was removedby filtering. The solvent was removed under reduced pressure and theresidue was purified through column chromatography (silica gel,hexane/ethyl acetate=2/1) to obtain4-(4-cyanophenyl)-2,6-dimethylquinoline (1.013 g) represented by thefollowing chemical formula (48).

The 4-(4-cyanophenyl)-2,6-dimethylquinoline (1.1 g), N-bromosuccinimide(1.516 g), benzoyl peroxide (165 mg), and CCl₄ (20 ml) were mixed andheated and refluxed for 1.5 hours in a nitrogen atmosphere. The reactionsolution was cooled to room temperature and the succinimide produced bythe reaction was removed by filtering. The solvent was removed underreduced pressure and the residue was purified through columnchromatography (silica gel, hexane/ethyl acetate=4/1) to obtain4-(4-cyanophenyl)-2,6-bis(bromomethyl)quinoline (0.098 g).

A toluene (1 ml) solution of4-(4-cyanophenyl)-2,6-bis(bromomethyl)quinoline (0.095 g) and triethylphosphite (1 ml) was heated for 2.5 hours at a temperature of 140° C.The reaction solution was cooled to room temperature and excessivetriethyl phosphite and toluene were removed to obtain a coarse productof Wittig reagent of 4-(4-cyanophenyl)-2,6-bis(bromomethyl)quinoline.

A DMF (2 ml) solution of the coarse product of Wittig reagent of4-(4-cyanophenyl)-2, bis(bromomethyl)quinoline andN,N-dimethylaminocinnamaldehyde (0.120 g) was dropped to a mixture ofsodium t-butoxide (0.090 g) and DMF (2 ml) in a nitrogen atmosphere atroom temperature and stirring was performed for 3 days at roomtemperature. Water was added to the reaction solution and the producedprecipitate was filtered. The precipitate was washed using CCl₄ waterand vacuum dried to obtain a compound represented by the chemicalformula (38) (0.125 g).

Example 1-7

Synthesis of a Compound Represented by the Chemical Formula (39)

In example 1-7, a compound represented by the chemical formula (39) wassynthesized through the following processes as an example quinolinederivative.

Magnesium (1.60 g) was added to THF (60 ml) in a nitrogen atmosphere and3,5-bis (trifluoromethyl)phenylbromide (17.58 g) was dropped. Theresulting mixture was stirred for 30 minutes at room temperature and aTHF solution of 3,5-bis (trifluoromethyl)phenylmagnesiumbromide wasprepared. In a nitrogen atmosphere, 4-chloro-2,6-dimethylquinoline (2.88g) and Ni(dpp)Cl₂ (500 mg) were added to THF (30 ml) and dispersed. TheTHF solution of 3,5-bis(trifluoromethyl)phenylmagnesiumbromide preparedas above was dropped to the suspension and the resulting solution wasstirred for 4 days at room temperature. Water was poured into thereaction solution, impurities were filtered, and extraction wasperformed using AcOEt (ethyl acetate). A drying process was appliedusing Na₂SO₄ and the solvent was removed under a reduced pressure. Theresidue was purified through a silica gel column (hexane/ethylacetate=3/2) to obtain4-(3,5-bis(trifluoromethyl)phenyl)-2,6-dimethylquinoline (4.40 g)represented by the following chemical formula (49).

4-(3,5-bis(trifluoromethyl)phenyl)-2,6-dimethylquinoline as representedby the chemical formula (49), N-bromosuccinimide (3.85 g), benzoylperoxide (400 mg), and CCl₄ (50 ml) were heated and refluxed in anitrogen atmosphere for 3 hours. The reaction solution was cooled toroom temperature and the succinimide produced through the reaction wasremoved by filtering. The solvent was removed under reduced pressure andthe residue was purified through column chromatography (silica gel,hexane/ethyl acetate=4/1) to obtain4-(3,5-bis(trifluoromethyl)phenyl)-2,6-bis(bromomethyl)quinoline (0.353g).

A toluene (2 ml) solution of4-(3,5-bis(trifluoromethyl)phenyl)-2,6-bis(bromomethyl)quinoline (0.100g) and triethyl phosphite (2 ml) was heated for 2.5 hours in a nitrogenatmosphere at a temperature of 140° C. The reaction solution was cooledto room temperature and excessive triethyl phosphite and toluene wereremoved to obtain a coarse product of Wittig reagent of4-(3,5-bis(trifluoromethyl)phenyl)-2,6-bis(bromomethyl)quinoline.

A DMF (2 ml) solution of the coarse product of Wittig reagent of4-(3,5-bis(trifluoromethyl)phenyl)-2,6-bis(bromomethyl)quinoline andN,N-dimethylaminocinnamaldehyde (0.067 g) was dropped to a mixture ofsodium t-butoxide (0.073 g) and DMF (2 ml) in a nitrogen atmosphere atroom temperature, and the resulting solution was stirred for 1 day atroom temperature. Water was added to the reaction solution and theproduced precipitate was filtered. The precipitate was washed using CCl₄water and vacuum dried to obtain the compound represented by thechemical formula (39) (0.058 g).

Example 2-1

Using the compound represented by the chemical formula (20) and createdin the example 1-1 as a doping material, an organic electroluminescenceelement was created through the following process. The structure of theproduced element is identical to that shown in FIG. 1. On a glasssubstrate 10, which is a transparent substrate, an ITO electrode wasformed as a first electrode 12 and a hole transport layer, an emissivelayer, an electron transport layer were formed as the organic compoundlayer 14 in that order over the ITO. The hole transport layer was formedby vacuum evaporating TPTE to a thickness of 600 Å. On top of the holetransport layer, a layer in which the compound of the example 1-1represented by the chemical formula (20) was doped to 0.8 weight % intoan Alq₃ (chemical formula (3)) which is the host material was evaporatedto a thickness of 400 Å to form the emissive layer. Then, Alq₃ wasevaporated to a thickness of 200 Å to form the electron transport layer.Finally, a LiF/Al electrode were formed as the second electrode 16 bysequentially evaporating LiF and Al, to complete an organic EL element.

The organic EL element thus obtained was driven at room temperature in anitrogen atmosphere. When the organic EL element was driven with acurrent density of 11 mA/cm², light emission with a luminance of 300cd/m² was achieved. The emitted light was orange. The luminancehalf-life when the element was driven with a current density of 110mA/cm² was approximately 40 hours.

Example 2-2

An element was created under conditions similar to the example 2-1except that the compound represented by the chemical formula (34) andcreated in the example 1-2 was used as the doping material instead ofthe compound represented by the chemical formula (20) and used in theexample 2-1. The obtained organic EL element was driven at roomtemperature in a nitrogen atmosphere. With a current density of 11mA/cm², light emission with a luminance of 350 cd/m² was achieved. Theemitted light was red. The luminance half-life when the element wasdriven with a current density of 110 mA/cm² was approximately 40 hours.

Example 2-3

An element was created under conditions similar to the example 2-1except that the compound represented by the chemical formula (36) andcreated in the example 1-3 was used as the doping material instead ofthe compound represented by the chemical formula (20) and used in theexample 2-1. The obtained organic EL element was driven at roomtemperature in a nitrogen atmosphere. With a current density of 11mA/cm², light emission luminance of 450 cd/m² was achieved. The emittedlight was red. The luminance half-life of the element when the elementwas driven with a current density of 110 mA/cm² was approximately 50hours.

Comparative Example 1

In a structure similar to that shown in FIG. 1, an ITO electrode wasformed as the first electrode 12 on a glass substrate 10 and an organiccompound layer 14 (comprising a hole transport layer and an emissivelayer which also functions as the electron transport layer) was formedon the ITO. The hole transport layer was formed by vacuum evaporatingTPTE to a thickness of 600 Å. On top of the hole transport layer, anemissive layer which also functions as the electron transport layer wasformed by evaporating Alq₃ represented by the chemical formula (3) to athickness of 600 Å. Finally, LiF/Al electrode was evaporated as thesecond electrode 16 to complete an organic EL element. This element wasdriven at room temperature in a nitrogen atmosphere. When the elementwas driven with a current density of 11 mA/cm², a light emissionluminance of 250 cd/m² was achieved. The emitted light was green. Theluminance half-life of the element when the element was driven with acurrent density of 110 mA/cm² was approximately 50 hours.

Comparative Example 2

An organic EL element was created under the conditions similar to theexample 2-1 except that a known porphyrin derivative represented by thechemical formula (50),

was used as the doping material instead of the compound represented bythe chemical formula (20). The element was driven at room temperature ina nitrogen atmosphere. When the element was driven with a currentdensity of 11 mA/cm², a light emission luminance of 100 cd/m² wasachieved. The emitted light was red. The luminance half-life of theelement when the element was driven with a current density of 110 mA/cm²was only approximately 10 hours.

Upon comparison of the examples 2-1˜2-3 and the comparative examples 1and 2, it can be seen that by using the quinoline derivative accordingto the present invention as the doping material for the emissive layer,light in the yellow˜red range having a wavelength longer than greenlight can be produced. It can also be seen that significantly higherlight emission luminance can be achieved with the elements of theexamples 2-1˜2-3, compared to the comparative examples 1 and 2.Furthermore, the luminance half-lives in the examples are similar tothat in the comparative example 1 (Alq₃) which currently is consideredto have a high stability.

Example 3-1

An organic electroluminescence element was created through the followingprocess using as the doping material the compound represented by thechemical formula (36) created in the example 1-4. The structure of theelement was identical to that shown in FIG. 2. On a glass substrate 10as the transparent substrate, an ITO electrode was formed as a firstelectrode 12 and a hole transport layer 22, an emissive layer 24, and anelectron transport layer 26 were formed on the ITO in that order as theorganic compound layer 14. The hole transport layer 22 was formed byvacuum evaporating TPTE to a thickness of 500 Å and evaporating a layerin which the compound of the example 1-4 and represented by the chemicalformula (36) were doped in 1.0 weight % to TPTE as the host material toa thickness of 100 Å, to form a two-layer hole transport layer 22 of aTPTE single layer and a doped layer. On top of the hole transport layer,DPVBi was evaporated to a thickness of 200 Å to form an emissive layer24. Then, Alq₃ was evaporated to a thickness of 400 Å to form anelectron transport layer 26. Finally, LiF and Al were sequentiallyevaporated to form a LiF/Al electrode as the second electrode 16 tocomplete an organic EL element.

The organic EL element thus obtained was driven at room temperature in anitrogen atmosphere. When the element was driven with a current densityof 11 mA/cm², a light emission luminance of 800 cd/m² was achieved. Theemitted light was white. The luminance half-life when the element wasdriven with a current density of 110 mA/cm² was approximately 50 hours.

Example 3-2

An organic EL element was created under the conditions similar to thosein the example 3-1 except that the compound created in the example 1-5and represented by the chemical formula (38) was used as the dopingmaterial instead of the compound represented by the chemical formula(36) which was doped to the hole transport layer in the example 3-1. Theorganic EL element thus obtained was driven at room temperature in anitrogen atmosphere. When the element was driven with a current densityof 11 mA/cm², a light emission luminance of 800 cd/m² was achieved. Theemitted light was white. The luminance half-life when the element wasdriven with a current density of 110 mA/cm² was approximately 50 hours.

Example 3-3

An organic EL element was created under the conditions similar to thosein the example 3-1 except that the compound created in the example 1-7and represented by the chemical formula (39) was used as the dopingmaterial instead of the compound represented by the chemical formula(36) which was doped to the hole transport layer in the example 3-1. Theorganic EL element thus obtained was driven at room temperature in anitrogen atmosphere. When the element was driven with a current densityof 11 mA/cm², a light emission luminance of 900 cd/m² was achieved. Theemitted light was white. The luminance half-life when the element wasdriven with a current density of 110 mA/cm² was approximately 100 hours.

(Evaluation of White Color Emission)

The result of evaluation of the white color emission from the elementcreated in the example 3-1 will now be described. In a white lightemitting element as shown in example 3-1 in which the compoundrepresented by the chemical formula (36) was doped to the hole transportlayer with TPTE as the primary constituent and in which DPVBi was usedin the emissive layer, the measurement result of the chromaticitycoordinates were X=0.33 and Y=0.33, which indicates the approximatecenter of the white color region.

On the other hand, the chromaticity coordinates of the light emissioncolor of the DPVBi alone were X=0.16 and Y=0.21. The chromaticitycoordinates for the light emission color of the compound represented bythe chemical formula (36) were X=0.51 and Y=0.46. From these results, itcan be seen that the chromaticity coordinates of the light emissioncolor of the white light emitting element obtained by combining theselight emission colors were on a line segment which linearly connectsrespective chromaticity coordinates of the two materials when usedalone. Moreover, the white light emission obtained by combining twomaterials such as in the example 3-1 changes depending on the dopingconcentration of the quinoline derivative compound represented by thechemical formula (36), thickness of the doped hole transport layer, andthe thickness of the blue emissive layer.

Therefore, in the white color light emitting element according to thepreferred embodiments of the present invention, the chromaticitycoordinates of “white” can be adjusted to desired values by adjustingthese conditions, that is, the doping concentration, thickness, materialfor the hole transport layer, etc.

Another factor which changes chromaticity coordinate values is thematerial for the hole transport layer. The chromaticity coordinates whenthe quinoline derivative compound represented by the chemical formula(36) was doped to the hole transport material TPTE used in the example3-1 were equal to the chromaticity coordinates X=0.51 and Y=0.46 of thecompound represented by the chemical formula (36) alone. In contrast,when α-NPD was used as the hole transport layer and the compoundrepresented by the chemical formula (36) was doped into the holetransport layer, the chromaticity coordinates became X=0.59 and Y=0.40,and, thus, there is a tendency that red becomes more intense. Asdescribed, the light emission color also changes depending on thecomposition of the material which is the primary constituent of the holetransport layer. The element structure when α-NPD was used as theprimary constituent of the hole transport layer was identical to that inthe example 3-1 except for the material.

(Advantage of Invention)

According to the present invention, a novel quinoline derivativecompound can be obtained in which at least two of substituents R₁˜R₇ ina compound represented by a general chemical formula (1) are substitutedby a substituent represented by the chemical formula (2).

Because this quinoline derivative has a molecular structure such thatthe conjugate system is long, light emission with high luminance and ofyellow red range is possible. Also, the quinoline derivative ischemically stable. Therefore, by employing this new material, forexample, as a material having a light emission function (material forthe emissive layer or material to be doped to the emissive layer) in anorganic EL element, it is possible to realize an organic EL elementhaving high luminance, high light emitting efficiency, and long lifetime.

Not only does the quinoline derivative of the present invention emitlight in the yellow˜red range when used alone, but the quinolinederivative also produces light in similar wavelength regions in a holetransport layer when doped to the hole transport layer. Therefore, bydoping the quinoline derivative to the hole transport layer of anorganic EL element, light can be emitted having a color synthesized fromthe light from the emissive layer and the light from the hole transportlayer. For example, by employing a blue light emitting material in theemissive layer and employing the quinoline derivative compound of thepresent invention as the doping material to the hole transport layer, itis possible to obtain an organic EL element having a white lightemission characteristic through synthesis of the blue light from theblue emissive layer and the light in the orange˜red range from the holetransport layer. In such a case, a synthesis color with the light fromthe emissive layer can be achieved by simply doping the hole transportlayer, and thus there is no need to separately provide an additionalemissive layer.

Moreover, it is possible to further improve the light emissionefficiency, stability, or the like by introducing a desired functionalgroup to the substituent in the compound of the present invention suchas, for example, introducing an electron attracting susbtituent in thesubstituent other than the substituents R₁˜R₇ of chemical formula (1)substituted by the substituent represented by the chemical formula (2).

Industrial Applicability

The organic compound according to the present invention is suited as alight emitting material, for example, for a light emitting material ofan organic electroluminescence element and material for other electronicdevices.

What is claimed is:
 1. A quinoline derivative compound represented by the following general chemical formula (1),

wherein groups represented by the following chemical formula (2) are introduced to at least two of the substituents R₁-R₇ in the chemical formula (1),

the number n of double bonds is 2 or greater in at least one of the introduced groups represented by the chemical formula (2); Q in the chemical formula (2) is an aromatic group having carbon or a heteroatom in the skeleton of the ring; and substituents R_(n) and R′_(n) in the chemical formula (2) are independent functional groups which are identical or different, or the substituents R_(n) and R′_(n) are cyclized by a saturated bond with each other or with an adjacent group.
 2. An organic compound according to claim 1, wherein at least one of the substituents R₁-R₇ in the chemical formula (1) other than the substituents represented by the chemical formula (2) is an electron attracting substituent.
 3. An organic compound according to claim 2, wherein the aromatic group Q in the chemical formula (2) has at least one of the substituents R_(Q); and at least one of the substituents R_(Q) is an electron donating substituent.
 4. An organic compound according to claim 3, wherein the substituent R₃ in the chemical formula (1) is an electron attracting substituent and the substituent Q in the chemical formula (2) is an electron donating substituent.
 5. An organic compound according to claim 4, wherein the substituent R₃ in the chemical formula (1) is a cyano group and the substituent Q in the chemical formula (2) is a p-aminophenyl group.
 6. An organic electroluminescence element in which an organic compound layer including an emissive layer is formed between two electrodes, wherein the organic compound layer includes an organic compound according to claim
 5. 7. An organic electroluminescence element according to claim 6, wherein the organic compound layer comprises a hole transport layer and an emissive layer, and the organic compound is doped to the hole transport layer.
 8. An organic electroluminescence element in which an organic compound layer including an emissive layer is formed between two electrodes, wherein the organic compound layer comprises a blue light emitting layer and a hole transport layer into which an organic compound according to claim 5 is doped, and the organic electroluminescent element emits white light.
 9. An organic compound according to claim 3, wherein the number n of the double bonds is 2 or greater in all of the introduced sub stituents represented by the chemical formula (2).
 10. An organic compound according to claim 9, wherein the number n of the double bonds is 5 or less in at least one of the introduced substituents represented by the chemical formula (2).
 11. An organic compound according to claim 9, wherein the substituent R₃ in the chemical formula (1) is a cyano group and the substituent Q in the chemical formula (2) is a p-aminophenyl group.
 12. An organic electroluminescent element in which an organic compound layer including an emissive layer is formed between two electrodes, wherein the organic compound layer includes an organic compound according to claim
 11. 13. An organic electroluminescence element according to claim 12, wherein the organic compound layer comprises a hole transport layer and an emissive layer, and the organic compound is doped to the hole transport layer.
 14. An organic electroluminescence element in which an organic compound layer including an emissive layer is formed between two electrodes, wherein the organic compound layer comprises a blue light emitting layer and a hole transport layer into which an organic compound according to claim 11 is doped, and the organic electroluminescence element emits white light.
 15. An organic compound according to claim 9 wherein the number n of the double bonds is 3 or less in the substituents represented by the chemical formula (2).
 16. An organic compound according to claim 15, wherein the substituent R₃ in the chemical formula (1) is a cyano group and the substituent Q in the chemical formula (2) is a p-aminophenyl group.
 17. An organic electroluminescence element in which an organic compound layer including an emissive layer is formed between two electrodes, wherein the organic compound layer includes an organic compound according to claim
 16. 18. An organic electroluminescence element according to claim 17, wherein the organic compound layer comprises a hole transport layer and an emissive layer, and the organic compound is doped to the hole transport layer.
 19. An organic electroluminescence element in which an organic compound layer including an emissive layer is formed between two electrodes, wherein the organic compound layer comprises a blue light emitting layer and a hole transport layer into which an organic compound according to claim 16 is doped, and the organic electroluminescence element emits white light.
 20. An organic electroluminescence element in which an organic compound layer including an emissive layer is formed between two electrodes, wherein the organic compound layer includes an organic compound according to claim
 9. 21. An organic electroluminescence element according to claim 20, wherein the organic compound layer comprises a hole transport layer and an emissive layer, and the organic compound is doped to the hole transport layer.
 22. An organic electroluminescence element in which an organic compound layer including an emissive layer is formed between two electrodes, wherein the organic compound layer comprises a blue light emitting layer and a hole transport layer into which an organic compound according to claim 9 is doped, and the organic electroluminescence element emits white light. 